Transportation Acceleration Loading 1

[jtseng123]

All,
PIP Industry Practice VESV1002, Design Criteria for Vessels, Section 4.2.8, Table 1 shows g loading for shipping modes (attached).
Is it the total final load to be used for shipping saddle design ? or additional vertical dead weight shall be added ?

I have seen vendor adding one more g to the vertical acceleration to account for dead weight. Though doing that is fine, but not sure if it is necessary. Anyone has insight of that table ?

 

[marty007]

I'm not familiar with the PIP standard on this, but here is another comparison for your reference.

Attached is the transportation load table from the Pressure Vessel Design Manual by Dennis Moss (3rd Ed).

Take a look at Table 7-3, and look at the loads per saddle in the y-direction. Within the brackets you have the term (Ws+Fy), where Fy is defined above Table 7-2 as K*Ws. So in effect, the total load they recommend considering is Ws(1+K), where K is the factor that depends on mode of transportation. So, you have to add dead load to the transportation acceleration.

The vertical factor for both road and rail are comparable in PIP to the values included in the Pressure Vessel Design Manual, so I suspect you should be using the same approach.

 

[jtseng123]

Marty, sounds right. Dead weight shall be added to vertical load, but upward load will be reduced by one g that the size of tie down cable will be smaller, not conservative.

 

[Trestala]

I believe that Note 2 on the table of your attachment specifies that 1g is already incorporated on the downward acceleration values. Also, we prefer to use the acceleration values provided by the freight forwarder, if available.

 

[jtseng123]

No. Note 2 only explains what "g" means.

 

[Trestala]

What I meant is that you don't need to add another 1.0g to the downward acceleration values in the table.

You have 2.0g in the ship, so you'll use 3.0g in the downward acceleration? So what you mean to say the the ship can accelerate downward 29.42 m/s2? That is too much from any of my past experiences.

 

[AWDMIKE]

For what it's worth, the 4th edition of the Pressure Vessel Design Manual has the same transportation load coefficients and the same equations.

On a recent project we were asked to comply with the factors from the following link:

https://www.fmcsa.dot.gov/regulations/cargo-securement/cargo-securement-rules

The equipment in question was shipped from Oklahoma to Michigan via truck.

 

[jtseng123]

The above FMCSA seems misses the critical vertical up and down loads, which is the most concern for ocean shipment. We purchase a lot of pressure vessels from Asian and shipped to US every year.

 

[AWDMIKE]

You are right. We considered the FMCSA loads as another set of shipping criteria, in addition to the ones we received from other shipping parties.

 

[dhengr]

Jtseng123:
The two different sets of criteria, ASME and FMCSA shown above are two completely different animals. The ASME criteria are intended to indicate transport loads which might be induced on pressure vessels and the like during transit, and we should design our vessels for these possible loads. The FMCSA criteria are intended to insure that any given load does not shift on or fall off of a hauler/trailer in transit. And, the assumption is that the hauler/trailer better be strong and stable enough to handle these loads. Two completely different considerations, although they are about the same range of magnitudes.